1. Field of the Invention
This invention relates to a photosensitive semiconductor device like a photocoupler and a method of manufacturing the photosensitive semiconductor device.
2. Description of the Related Art
A photocoupler for transmitting a signal with light as a medium is provided with a light-emitting device for converting an electric signal into a lightwave signal and a light-receiving or -detecting device for converting light emitted from the light-emitting device into an electric signal.
A light-emitting surface of the light-emitting device and a light-detecting surface of the light-detecting device face each other and they are held within a casing.
As one example of this casing, there is known a casing having a double mold structure which comprises an inward mold resin portion and an outward mold resin portion for covering the inward mold resin portion.
The inward mold resin portion is composed of a mold resin having a light-transmissive property. The inward mold resin portion is charged between both devices without inhibiting the transmission of a lightwave signal between both devices. Further, the inward mold resin portion serves so as to position both devices in a predetermined posture and improve electrical insulating properties thereof owing to the direct covering of their electrical connecting portions therewith.
The outward mold resin portion is composed of a mold resin having a lightproof property. The outward mold resin portion serves so as to perform a lightproof effect for preventing the entrance of externally-incoming light between both devices owing to the covering of the inward mold resin portion therewith. The lightproof effect of the outward mold resin portion prevents the mixing of noise between both devices due to the externally-incoming light.